Altered loading is a causative factor for the development of knee osteoarthritis following anterior cruciate ligament reconstruction (ACLR), and real-time biofeedback may be an effective intervention to manipulate altered mechanical loading about the knee. The purpose of this study is to 1) determine if ACLR participants are able to acquire and retain various loading patterns using real-time biofeedback, 2) determine the effect of altered loading on lower extremity biomechanics during walking gait, and 3) determine the effect of altered loading on biochemical markers of collagen turnover and inflammation during walking gait.

Participants will attend 4 testing sessions. Lower extremity biomechanical outcomes and blood samples will be taken before and following the participant walking at a self-selected speed for 20 minutes. During the 20 minutes of treadmill walking real-time biofeedback will be displayed in an attempt to alter mechanical loading. Participants will complete a control, overloading, under-loading, average loading testing session. Order of loading condition will be randomized.

Inclusion Criteria:

• Have a history of a primary, unilateral ACLR using either a hamstring or patellar tendon autograft, cleared by a physical for full return to physical activity with no limitations, and participate in at least 30 minutes of physical activity 3 times per week

Exclusion Criteria:

• History of injury to either leg, other than ACLR (e.g. ankle sprain, muscle strain), within 6 months prior to participation in the study, history of lower extremity surgery other than ACLR, history of osteoarthritis or current symptoms related to knee osteoarthritis (e.g. pain, swelling, stiffness), currently pregnant, or planning to become pregnant while enrolled in the study, cardiovascular restrictions that limit the participant's ability to participate in physical activity.